The role of the Microarray Core will be to carry out genome-wide analyses of transcriptional changes and of gene copy number changes that result from either experimentally induced or clinically arising aberrations in genes that regulate genomic stability, cell survival, cell cycle signaling and developmental maturation in T cell oncogenesis. Gene expression profiling will be carried out on specimens from projects 1, 2 and 4, as a means to discover the transcriptional consequences of perturbing molecules that are critical in these processes. Array Comparative Genomic Hybridization will be performed to detect and quantify gene loss and gene amplification in tumors from experimental animals in project 4. It is anticipated that both types of microarray studies will identify genes whose activity, and in some cases, structure, are disrupted by abnormalities in the key regulatory proteins involved in T cell malignancy. The following services will be provided by the Microarray Core: 1. Starting with RNA provided by investigators, produce transcriptional profiling data using mouse or human oligonucleotide microarrays. 2. Starting with genomic DNA provided by investigators, produce genomewide gene copy number determinations using mouse or human oligonucleotide microarrays.